1. Field of the Invention
The present invention relates to an opthalmologic apparatus, and more specifically, to a technique for focusing in an opthalmologic apparatus.
2. Description of the Related Art
A technique about a fundus camera, which selects and uses a plurality of illumination light sources, is discussed in Japanese Patent Application Laid-Open No. 09-066030. In this case, if an illumination light source is changed, it is necessary to improve visibility by changing the wavelength of index light. However, a difference in the length of the light path is generated due to the difference in the wavelength of the index light, so that it is difficult to confirm an accurate focal point. In the technique discussed in Japanese Patent Application Laid-Open No. 09-066030, the difference in the length of light path is absorbed by changing a relay lens of an illumination system according to the illumination light source.
However, since a relay lens barrel of the illumination system is large, it is difficult to replace the relay lens barrel while maintaining the accuracy of the optical system.